Wow, that took an age, and I'm not convinced it was "Configuring WIMBoot" all that time. The tablet just rebooted and is back to its former uncompressed state - so I suspect there's some issue with updating the status message.

I continued to experience difficulties upgrading and ultimately reinstalled Windows from a USB stick. Now I actually find that the internal SSD runs faster (and actually more than twice as fast as previously with ZIPmagic, which topped out around 65MB/s read.) I get 80MB/s write and 150MB/s read from the SSD, and I added an ultra-fit 128Gb USB3 stick which runs at about the same speed. The USB stick cost less than ZIPmagic.

I am not surprised, as I indicated earlier, ZIPmagic is 100% compatible with Redstone and would not be blocking your upgrade.

As to your performance concerns - ZIPmagic is currently optimized for space instead of speed. You may optimize it for speed by taking the following steps:

1) Use MaxSpeed compression (based on the type of your SSD, you can use stronger compression - feel free to dig into this more).2) Disable NTFS compression (decompress your disk using DriveSpace after you've finished compressing with DoubleSpace).

That will accelerate your disk read speeds above what you get with your raw hardware.

The error I experienced initially when installing the Windows 10 Anniversary Update went away after removing ZIPmagic, there was another error seemingly related to a device not "functioning properly" before I started again with a fresh install.

Be sure to decompress your disk using DriveSpace after you finish compressing with DoubleSpace - this will not harm DoubleSpace compression, and it will fully disable NTFS compression which is your speed killer (even if you selected MaxSpeed for DoubleSpace).